Fluid-operated percussive-tool.



L. BAYLBS.

FLUID OPBRATED PERCUSSIVE TOOL.

APPLICATION FILED JUNE 9, 1914.

Eatemed Feb. 2, i915.

Lewis c. Barnes,

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Specicatonof Letters Patent,

Patentedeb. 2, 19133.`

iApplication iiledJune a, 19111. `Seriallc..$413,926.

' To all whom it may concern .7

Y tain new and useful-Improvement inl.` Operated Percussive .l`ools,.ofwhich the fol-r lowing is a speciicatlon.

This invention relates to fluid operated percussive tools, and moreparticularly to tools of the type wherein the admission of iiuid iscontrolled primarily by theH movement of the piston. 'I

The object of this invention is to provide an auxiliary valve forcontrolling the admission of iiuid to one portion of the cylinder toincrease the eiiciency of the piston blow. This, object isv accomplishedbythe invention, a practical embodiment of which is shown in theaccompanying drawings, in which,

Figures 1 and 2 are 'longitudinal sections showing the pistonandauxiliary valve inI dii'erent positions.

ln the drawings is shown acylinder l which consists of a smaller'forward bore 2 and a' larger rearward bore 3.l In the cylinder 1 is apiston having a head 5 sliding in the rearward bore 3 and a hammer'bar 6sliding in the forward bore 2, therebeirig a neck 7 between the hammerbar'and the head of the piston. Fluid is admitted constantly to theforward endof bore@ by a passage 8. From the forward end of bore2,'somewhat rearward of the passage 8, a passage E? leads to therearward end of the bore 3. From the passage 8 a passage 10 leadsrearwardly along the cylinder, this passage having two ports, 11 andv12, open-l ing into the rearward end of bore 2, the forward of these,11, being so placed as to be uncovered by the hammer bar 6 and allow:duidto pass to the forward end of the bore 3, when the piston ispractically at the forward end of stroke, while the rearward port12'when open admits fluid for a considerable portion oi the pistonstroke, To control the port 1&2 a valve 13 is Iprovided which has a head14 sliding in a valve chest 15 and a. port controlling portion 16adafpted 'to project into port 12 and close it 'rom communication withpassage 10. The inner end'aof the valve chest 15 is connected with theforward end vof bore 3 by a passage 17', while the outer end isconnected with the rear lend ofl bore 3 by a pasagev 18.Anexhaustpassage 19 is providedfor both vends of the rear bore 3, itbeing soplaced as to be kuncovered by the piston near the 'en-d (if thepiston stroke. in each direction. p

1n operation, supposing the parts to be in the `positions shown in'iFig.1, air is being admitted .to the forwardend of bore 2 and lto the rearend'. ofv bore 3 through the passage 9. Allnder such conditions therewill be pressure inthe. outerven'd of valve chest 15 and no pressure inthe inner end, `the forward end of bore 8 being open to atmospherethrough portA 19. The pressure in the rear end ofbore on' the largerarea of the p1ston head, willdrivethe piston forwardly against thelpressure on the forward end of the hammerv bar 6, the fluid in thefront of bore -3 exhausting for part of the stroke through port 19. Asthe Ypiston moves ior-l wardly'the hammer bar 6 will cover the pas sage9 so that the fluid in the rear end of the bore 3 will act expansivelyto move the piston forward. Further movement of the piston will causethe hammer bar 6 to uncover the port 11. This will admit'air to theforward end ofv bore 3 and at the same time the exhaust port 19 will beuncovered by the rear face 'of the piston head exhausting the rear endof the cylinder and also the youter end of the valve chest 15 throughthe passage 18. The pressure in the inner end .Y

of the valve chest 15 through-the passage 1'7 and also the pressure onthe end of the port controlling portion 16 will move the` valve 13outwardly opening th port 12. vThis will allow .fluid to enter the frontend of the bore 3 for a considerably longer period during the backstroke than during the forward stroke-and thus will produce a full.

backward stroke of the piston, while by reason of the fact that the port12 is closed during the forward stroke, the piston will strike a muchharder blow on account of the absence of a live air cushion in the frontend of kbore 3.

lt is to be understood that while the present showing and descriptiondisclosesonly one specified modification of the invention, other formsand modifications are included in the spirit and scope of the inventionas expressed in the claims.

lVhat I claim is: 1. ln a percussive tool, a cylinder, having a largerrearward portion and a smaller forward portion, a pistn in said cylinderhaving a head in said rearward cylinder portion and a hammer bar insaid-forward cylinder portion,l means for admitting fluid constantly tothe forward end of said cylinder', a passage controlled by the pistonfor admitting Huid to the rearward end of said larger cylinder portion,a passage for admitting fluid to the forward end of said larger'cylinderportion,' a valve 'controlling said passage, and means for moving saidvalve tu open said passage near the forward end of the piston stroke. i

2. In a percussive tool, a cylinder, a piston having two smallersurfaces for driving it in one dii ction and a larger surface fordriving it in the other direction, means for admitting pressureconstantly to one of said smaller surfaces, means for admitting fluidintermittently to the other ofsaidsm'aller surfaces comprising a valve,and means Ifor admitting fluid intermittently to said larger surface.

3. In a percussive tool, a cylinder, a piston having a head and a hammerbar, means for admitting fluid to exert a constant pressure on theforward end of said hammer bar,

means controlled by said piston fQr admitvting fluid intermittently toeXert pressure on the rear of said piston head, and means com a prisinga valve for admitting fiuid intermittently to exert pressure on theforward face oi said piston head.

4. In a pereussive tool, a cylinder, a piston having a head and a hammerbar, means for 3 exerting a constant fluid pressure on the for Ward endof the hammer bar, means for eX- erting an intermittent fluid pressureon the rearward face of said piston head, and means for exerting anintermittent pressure on the 4 forward face ofsaid piston headcomprising a valve.

5. Ina percussive tool, a cylinder, a piston having a head and a hammerbar, means for exerting a constant. fluid pressure on the f forward' endof the hammer bar, means for exerting an intermittent fiuid lpressure onthe rearward `face of said piston head, and

p means for exerting an intermittent pressure on the forward face ofsaid piston head. i

In testimony whereof, I have hereunto set my hand.

LEWIS C. BAYLES. Witnesses:

FRED S. OVERTON, OTTO W. HOLMGREN.

